High frequency power circuit



Aug. 17, 1965 c. J. WEIDKNECHT HIGH FREQUENCY POWER CIRCUIT OriginalFiled Oct. 21, 1959 2 Sheets-Sheet 1 .69 z n E /4 5 a? 1/ K? a! /0 IIIINVENTOR Ckarles .zmw;

ATTORNEYS Aug. 17, 1965 c. J. WElDKNECHT HIGH FREQUENCY POWER CIRCUIT 2Sheets-Sheet 2 Original Filed Oct. 21, 1959 INVENT OR Mm w 6% flag J/United States latent O ice 3,261,711 HIGH FREQUENCY PGWER CEECUITCharles J. Weidlmecht, Willow Grove, Pa, assignor, by mesne assignments,to United Aircraft Corporation, a corporation of Delaware Originalapplication (lot. 21, 1959, Ser. No. 847,814, new Patent No. 3,074,024,dated Jan. 15, 1963. Divided and this application Sept. 22, 1961, Ser.No. 140,129

17 Claims. ((31. 33l--56) This invention is a division of applicationSerial No. 847,814, filed Gctober 21, 1959, 3,074,024, January 15, 1963,for High Frequency Power Circuit, and generally relates to improvementsin electron tube circuitry for high frequency alternating currentsignals. The invention particularly concerns such improvements elfectiveto increase the power handling capacity of electron tubes thereby toreduce the size, Weight and complexity of the circuits.

In constructing electronic amplifiers, transformers, transmitters, andsimilar circuitry, employing electron tubes, the size and weight of theoverall equipment is to a great extent determined by the size and Weightof the tubes which in turn, as presently manufactured, greatly increasein size with increased power rating. One of the important reasons forthis rapid increase in tube size that is somewhat out of proportion tothe increase in power handling capability, is the relatively inetficientway in which presently designed tubes are cooled or constructed todissipate heat. Among the various techniques, there is provided theliquid cooled varieties of tubes where a cooling fluid is circulated ina bath about the tube body or about portions of the tube to receive andcarry away the heat. Another technique is to provide a multiple finstructure located outside the tube envelope and connected to the plateor other power carrying electrode to dissipate the heat by radiation. Insome instances, such fins alone are not adequate for cooling the tubeand a motor driven fan is used to circulate air over the fins to enhancethe cooling elfect.

Obviously, such cooling techniques as have been previously practiced arenot the most efficient means for COOling the tube from a heat transferstandpoint and a considerably more effective technique for doing sowould be to directly connect the power handling element or electrode inthe tube to a large heat sink, such as the chassis of the circuit, andthereby more effectively cool the tube by means of conduction.

To obtain this desired and improved cooling function according to thepresent invention, there is provided a novel manner of electricallyinterconnecting the circuit elements of a high frequency electronicamplifier or related circuit whereby the power carrying electrode of thetube may be connected directly to a heat sink chassis and thereby conveythe heat away from the electrode both rapidly and efficiently. However,in order to provide this function, the plate or other power handlingelectrode must also be grounded with respect to both the alternatingcurrent and direct current signals of the power being handled by thetube. According to the present invention, this grounded power electrodeconfiguration is made possible by interconnecting the circuit elementsin such manner that the input and output circuits are decoupled andproperly isolated from the direct current power sources thereby topermit proper functioning of the circuit despite the grounded powerelectrode connection.

It is accordingly a principal object of the invention to provide a highfrequency electronic circuit having components of standard size andweight interconnected to handle increased power without the need forauxiliary cooling equipment.

A further object is to reduce the size and weight of an diillflllatented Aug. 1?, i965 electronic circuit employing standard andavailable tubes and components. 7

Still another object is to provide an electron tube circuitconfimrration with the power carrying electrodes of the tubes beingphysically and electrically grounded to a heat sink chassis to provideconduction cooling of the electrode and tube.

Other objects and many additional advantages will be more readilyunderstood by those skilled in the art after a detailed consideration ofthe following specification taken with the accompanying drawings,wherein:

FIG. 1 is an electrical schematic diagram illustrating a common gridelectron tube amplifier circuit embodying the present invention,

FIG. 2 is an electrical schematic diagram, similar to to FIG. 1 andillustrating the invention incorporated in a common cathode amplifiercircuit; and

FIGS. 3 and 4 are schematic illustrations of additional features of theinvention embodied in a triode vacuum tube common grid circuit and atetrode common cathode circuit, respectively.

Referring now to FIG. 1 for a detailed consideration of one embodimentof the invention, there is shown a high frequency amplifier circuitcomprising a single high vacuum electron tube ill of the triode variety,having a cathode electrode 11, a grid electrode 12, a cathode heater 1.3and a plate electrode 14. This tube may be of a Well known varietycommonly available on the open market and known as a planar power triodefor high frequency a plication. Such tubes are provided with an array ofheat radiating fins, 15 connected to the plate electrode, as generallyillustrated, for dissipating the heat.

In the customary use of this type ube as an amplifier or in a relatedcircuit, the plate electrode 14 is energized at both direct current andalternating current potentials far above ground potential and theelectrode becomes quite hot as a result of the bombardment of electrodesflowing from the cathode element 11. Consequently, the fin structure 15is used to radiate the heat being gen erated, and a motor driven fan mayalso be used to circulate cooling air past the fins 15 to aid inremoving the heat. However, according to the present invention the fins1,5 are physically and electrically directly connected by soldering orotherwise to the chassis heat sink structure, generally illustrated bythe symbol 16, with the resuit that the complete chassis for housing andsupporting all components of this circuit serves as a large heat sinkthat is directly connected to the plate electrode 14 to conduct away theheat from the plate much more efiiciently and rapidly than before.Consequently, by grounding the power handling electrode of the tube 19,this tube may function to control a flow of power many times greaterthan its rated capacity, or in other words, a much smaller power triodemay be used for a given application than heretofore with result that theoverall circuit may beconsiderably reduced in size and Weight over knownpower amplifying configurations, not to mention the further size andWeight savings being effected by eliminating. the need for a motordriven fan commonly used for cooling the fins 15.

Returning to FIG. 1 for an understanding of the circuit configuration,permitting this plate electrode '14 to be grounded to the chassis, thealternating current signal paths first will be described. The inputsignal is introduced to the primary winding 17 of an input transformerhaving secondary windings l8 and 19 interconnected in each leg leadingto the heater element 13. The upper terminals of each secondary 18 .and.19 are connected together by a capacitor 20 which provides a shortcircuit therebetween at the high frequency of the input signal, butprovides a high rea-ctance insofar as the lower frequency heatercurrents are concerned. The lower terminals of each secondary gether bycapacitors 21 and 22, lwhich'p'ossess a low re- .actance atthe highfrequency of the input signal but a higher reactance at the much lowerfrequency of the heater source 23. The cathode element 511 is connectedto the heater lines :as shown, and the capacitors 52-1 and 22 furtherserve to connect the lower terminals of the secondary windings :18 and19 to the grid circuit element. As thus far described, therefore it isevident that the high frequency input signal is introduced between thecathode electrode 1 1 and grid electrode 12 to control the flow ofelectrons to the vacuum tube 10.

To isolate the input signal from entering the heater source, and therebyto substantially eliminate the stray capacity to ground that wouldotherwise short circuit the secondary windings .18 and 19, there isprovided choice coils 24 and- 25, respectively, one in each, line of thewinding are also connected toheater connector leading to the heatersource 23. These I choke coils 24 and in cooperation with the capacitors25 and Y27, having one side grounded, form an effective [filterpreventing the high frequency input signal from entering the heatersource and being'grounded .by stray capacity.

On the other hand, the choke coils 2 4 and 25 as well as the secondarywindings 18 and 19 possess very low impedance at the frequency of theheater source 23,-

whereby the heater current passes through these components in acontinuous path to energize the filament '13 of the tube 10. 7

Considering the alternating current output circuit of the tube 10, theprimary winding of a tuned output transformer 28 has its left handterminal connected to capacitors 21 and 22 to the cathode circuit, sincethe reactance of the capacitors 21 and 22 is extremely low at thefrequency involved. The right hand terminal of transformer primarywinding 28 is connected to the grounded plate electrode 14 through acapacitor 29, also having negligible reactance at high frequency, Thusit is evident that primary winding ofoutput transformer 28 is connectedacross the tube from the plate electrode '14 to the cathode electrode 11and is energized according to the alternating current signal output ofthe tube 10,

Considering the direct currentcircuit paths for ener gizin g the tube,the positive terminal of the direct current supply 30 is directlyconnected to the chassis, as shown, thereby energizing the plateelectrode 1'4, also grounded as discussed above." From the plateelectrode 14, a direct current flows to the cathode :1'1 and through thetrans- 'former winding 19 and choke winding 25, both of the latterrepresenting substantially no res istance to the flow of direct current.After'passing through the choke winding 25, the'direct current flowsover the direct current return line .31 and thence to resistor 32 to thenegative terminal of the direct current source 30, thereby complet ingthe circuit. A direct current bias potential is also supplied to thegrid electrode :12 by connecting a'negative terminal of the directcurrent source 30 to the'grid circuit by means of a resistor 33 asshown.

-It is toibe particularly noted that this circuit configure tionsubstantially prevents the alternating current signal frompassing-through the direct current-power source 30 or low frequencyalternating current heater source 23. while at the same" time preventingthe direct current from passing through the output load transformer 28.The former isolation is necessary to prevent the alternating currentsignal from being shortcircuited to ground. through stray capacity inthe sources 30, and 23, which short cir: cuited connectionwo-uld disablethe high frequency circuit and prevent proper operation; q I J Thus inthe circuit illustrated in FIG. 1," there is provided a means forelectrically and physically grounding the plate electrode 14 directly tothe conducting chassis for both alternating current, direct current, andheat transfer purposes, thereby enabling'the tube to be operated and tohandle electrical power far above its rated power. capacity.

7 indicated as resistor to the heater source.

In FIG. -2, there is shown an alternative vacuum tube amplifier circuitconfiguration, that in common with the embodiment of FIG. 1, alsoenables the plate electrode 35' to be physically and electricallygrounded to the chassis at 3 6 to provide the advantages discussedabove.

In this alternative circuit configuration, the components are connecteddifferently to provide what might best be termed a common cathode typeamplifier. Tracing the alternating current input signals, the highfrequency input to the circuit is introduced to primary winding 37 of.an input transformer, having one side or terminal of which is groundedto the chassis. The secondary winding 38 is tuned by a capacitor 40 landthe upper terminal thereof is connected to the grid electrode 39 of thetube. The lower terminal of the secondary winding is connected through aresistor t1, paralleled by a capacitor 42, in a biasing circuitcomprised of a parallel connected resistor 43 and capacitor 44', Whoseopposite terminal is connected to the cathode electrode 45. As thus fardescribed, therefore, the input signal is coupledacross the control grid39 and cathode through suitable selfabiasing means.

In the alternating current signal output circuit, the primary winding 46of an output.transtormeutuned by a variable oapacitor lfi', is connectedbetween the cathode electrode and ground through a capacitor 48 of lowtrode 4,5, in turn, receives alternating currentfrom the 3 plateelectrode dd'which is physically and electrically grounded to thechassis 36 in the same manner as in FIG.

1. Thus an alternating current signal output circuit may 7 be tracedfrom ground 36 and through the tube from plate 35 to cathode 45 thencethrough parallel resistor 43 and capacitor 44, and through the primarywinding .46, and rfinally through capacitor 4-8 and :back to ground 36.The capacitor 43 also providesan alternating current shunt pat-h acrossthe direct current potential source 4-9, there- 'by preventing thealternating current signal from passing through the direct currentspotential source 49 or through the heater' source 52. v 1 I 1 The outputtransformer 46 is provi-ded'with two secondary windings 50 and 51, withwinding 563 being connected lit a line 53-leading between theheatersource 52 and the heater element '54 of the tube, andwith thesecondary Wll'ldlIlg 51 being connected to energize. a load generally55. The secondarywinding 56, lo cated in the heater line53, serves tointroduce an alternat: ing current bucking signal in the line 53 whichprevents the transmission of the alternating current output signal Analternating current bypass capacltor 56 also connects the heater line53to ground 36 to by-pass high frequency alternating current signals toprevent anysignal that succeeds in passing through the" secondarywinding 56 from reac-hingythe heater source 52.

FIG. 3 illustrates one preferred manner of electromechanicallyconstructing a circuit similar to FIG. -1 'for cathode 83, andheater'elements 84. 'As is common in this type tube 80, plate electrode81 has an outer terminal located at the upper end of the tube, the grid82 has an outer terminal physically located'midway along the length ofthe tube, and the terminals for cathode and heater electrodes 83. and 84are physically located at the base.

Enclosing and shielding the grid-cathode circuit of the tube isprovideda' sealed inner cavity container 85 ofconducting material, whichas shown, has an upper wall 86 hysically and-electrically connected withthe outer terminal of grid 82 and a'lower wall having an openingcommunicating with the inlet of a hollow conducting tube 88. This innercavity member 85 completely seals the grid cathode circuit of tube 39except for the opening communicating with hollow tube 83.

For energizing the heater elements and for injecting a high frequencyinput signal to the grid-cathode circuit, electrical connecting wires 91and 92 leading to these electrodes are directed downwardly through thehollow tube 88 and thence connect with the heater source 8? and the highfrequency input signal line 9%. More specifically, the heater lines 91and 92 are connected to choke coils 93 and 94, respectively, and thencepass upwardly through hollow tube 88 and through bifilar windings 5 and96, tuned by a slug 9% to the heater element $4 and cathode 83 which areconnected together as shown. The high frequency input signal over line9;} is injected into both lines 91 and 92 through capacitors 97 and 98,and is, therefore, also introduced to the cathode 33.

Considering the high frequency alternating current input to the tube,the alternating current input signal from line 90 is confined within theinner shielding cavity 85 in the inside of hollow tube 88 and introducedin the oathode to grid circuit of the tube 3% by means of a pi network,consisting of the inductance of the bitilar windings 95 and 96 and thedistributed capacity represented by the dotted line capacitors Tilt) andHill, existing between the inner surface of cavity 8-5 and lines 91 and92. This high frequency input signal is prevented from passingbackwardly into the heater source 8% by the choke coils 93 and M.

In the alternating current output circuit, there is provided a largeouter or main cavity container 1&4 Whose upper wall 165 is physicallyand electrically connected and sealed to the plate element of tube 8!).Thus as discussed above, the outer cavity container member rec forms arelatively large heat sink for thermally cooling the plate electrode 51of the tube. All other walls of the outer cavity M4 are closed andsealed except for the right hand wall 1% which is provided with upperand lower openings 167 and 108.

The upper opening 197 is made sufiiciently large to permit the hollowtube 88 to eXtend-therethrough, as shown, without contacting the wall136 of the outer container 104. In other words, there is provided aspacing between the two members or suitable insulation to electricallyisolate the tube 88 from the wall 1%. The lower opening Tilt; throughthe outer container 194 permits an insulated output line to enter thecavity and electrically connect with the outside hollow tube 88 throughan alternating current coupling capacitor lid as shown.

In this common grid configuration, alternating current output signalsflow from a plate electrode 81 of tube 86 to the control grid 32 withinthe tube and thence pass over the outside surface of the iner cavitycontainer 85 and over the outside surface of the conducting tube 88. Phehollow tube S3 is deliberately formed in a loop shape to provide aninductance at the high frequency of the signal. To tune this inductancein the output circuit, a small variable tuning capacitor 111interconnects the inner cavity member 85 with the side wall of the outercavity member 134. At the lower end of hollow tube 83, there is providedan additional capacitor 1E2. interconnecting the tube 88 with the outercavity Wall 1%. in addition, distributed capacity exists between thehollow tube 88 and the outer cavity 16 with the net result that the tube83 and various capacities mentioned, form a tuned output circuit for thealternating current signal. Consequently, the alternating current outputsignal appears on the outer surface of hollow tube 83 and is taken fromline 1% conmeeting with the outside of this hollow tube For providingdirect current energization and biasing of this circuit, a directcurrent power source 113 has its positive terminal grounded to the outercavity member Wall 186 and its negative terminal energizing a gridbiasing resistor 114 and a plate circuit resistor 115. The opposite endof biasing resistor 11 i connects with the hollow tube 88 leading to theinner cavity container and, in turn, leads to the control grid $2thereby establishing a direct current potential between the plate 81 andgrid 82. The opposite end of resistor 115 connects with line 92 leadingto the cathode 83 thereby establishing a direct current potentialbetween the plate and cathode of the tube.

Recapitulating the operation of the circuit of FIG. 3, there is providedan inner cavity 35 for the tube for containing and shielding the inputsignal between the control grid and cathode, and an outer cavity ill-*5for containing and shielding the alternating current output signal inthe plate to control the grid circuits. The alternating current inputsignal from line $6 is introduced in the inner cavity and is coupledbetween the control grid and cathode by a pi network comprising windings95 and and distributed capacity and Till.

In the alternating current output circuit, the signal is directed overthe outside of hollow tube 83 which is formed in a loop shape to providea distributed inductance and the distributed capacity from the hollowtube 88 to the inner walls of the outer cavity container 104 togetherwith the tuning capacitor 111 and lower capacitor 112 serve to tune thisinductance to the frequency range desired. The direct currentenergization is provided by a source 113 whose positive terminal isgrounded to the outer cavity 194 which in turn is connected to the plateelectrode 81 of the tube. The negative terminal thereof connects withplate resistor 115 to energize the plate to cathode circuit and withbiasing resistor 114 to bias the control grid 82. The alternatingcurrent, direct current, and low frequency heater signals are alldecoupled from one another by the chokes 93 and 94 and by capacitors,such as 117, across the direct current source 113.

FIG. 4 illustrates the electromechanical configuration of a distributedcomponent circuit similar to FIG. 3 but employing a high frequencypowered tetrode tube 12% in a common cathode circuit configuration. Ingeneral, the mechanical circuit arrangement is quite similar to that ofFIG. 3, but the electrical connections are varied to provide analternating current output signal taken from the plate-cathode circuitof tube 1259 rather than from the plate-control grid.

The tube is of the high frequency planar power type and comprises aplate electrode 121, a control grid 122, an additional grid 123, acathode 124, and heater 125. To contain and electrically shield thealternating current input signal circuit, there is provided an innercavity container 126 which is physically and electrically sealed to grid123, and completely encloses both of the grids and the cathode 124 andfilament 125 except for a lower inlet leading into a hollow tube 127through which the heater and cathode wires 12%, 129 and alternatingcurrent signal wire 13% may enter the inner cavity 126.

The alternating current input signal is conducted over line 139 anddirected to the control grid 122 through a pi network comprised of aninductance 13K tuned by a slug 132, and the distributed capacities 133and 134 existing between the inductance 131 and the inner cavity 126,being represented by dotted lines. The cathode electrode 124 isconnected to the additional grid 123 and thence to the inner cavity 126by a capacitor 135 which, at the frequency of the input signal, isessentially a short circuit. Consequently the alternating current inputsignal over line 13b is applied across the control grid 122 to cathodecircuit to energize the tube 12%.

In the alternating current output circuit, the cathode is coupled toinner cavity 126 by a capacitor 135, whereby the alternating currentsignal from the plate electrode to the cathode 124 is directed over theoutside of inner cavity 126 and thence over the outside of hollow tube127 that is formed in a loop shape, as in FIG. 3, to provide aninductance of the high frequency involved. This inductance is tuned bythe distributed capacity existing source 142 has its positive terminalconnected to the outer cavity 136 and thence to the plate electrode 121of electron tube 120, and its negativelterminal connected to a resistor143 connecting tothe cathode 124 over line 129. The negative terminal ofsource 142 alsois connected to a bias resistor 144 and decoupling choke145 to input line 130 leading to the control grid 122 and hence suppliesa negative direct current bias to the control grid 122. To providedirect current energization of the additional grid 123, a lessernegative potential, which may be taken from the tap 146 of the directcurrent source, is applied over line 147 to the hollow tube 127 leadingto the additional grid 123. Thisestablishes the additional grid at apositive potential with respect to the control grid 122 of the tube. 1 a.7

As in all of the circuits discussed above, the power carrying plateelectrode 121 is physically and electrically grounded to the outercavity136, whereby, the cavity walls constitute a large heat sinkchassis to dissipate the heat being generated in the electron tube andincrease the power handling capability of they ci'rcuiting components.The inner and outer cavities 126 and 136 also provide the necessaryshielding to both decouple, and isolate the different circuits andprovide the functions desired.

It is evident that relativelyfew of the. many possible circuit.configurations have been illustrated and described herein andaccordingly many modifications may be made 7 by those skill-ed in theart without departing from the spirit and scope of the invention.xAccordingly, this invention should be considered as being limited; onlyby the following claims.'

What is claimed is:

1. In a high frequency electronic circuit, an electron valve havinga'plurality of elements wherein electrons flow to a power carryingelements from a second element and at least one additional elementregulates the intensity of the electron flow, an inner cavity containerforming, an electrical shielded enclosure for said second element andsaid additional element and being directly connected to one of saidelements enclosed, means for injecting a high frequency signal into theinner cavity and applied across the elements enclosed therein, an outercavity container directly connected to said power carrying element andenclosing said inner cavity, tuned circuit output means interconnectingsaid inner cavity container and outer cavity container, and outputterminal means coupled to said tuned circuit. means and to said outercavity container for conveying an alternating output signal. t

2. In the circuit of claim 1, said means for. injecting the input signalincluding a hollow tube passing through the outer container cavity andopening into the'inner cavity, and said hollow tube being arcuatelyconfigured whereby its outside surface. provides an inductance for saidtuned circuit. a

3. In the circuit of claim 1, saidelectrbn .tube. comprising a planartriode wherein said second element is the cathode and said additionalelement is the control grid, and said inner cavity container is directlyconnected to the control grid. v v

4. In thecircuit of claim 1, said electron tube comprising a planartetrode where said second element is the cathode, and said additionalelement is a control grid, and having a second additional element as afurther grid, said inner cavity container being directly conoutputsignal.

nected to said further grid and capacitor coupled to said cathode,

5. In an electronic circuit, an electron valve having a plurality ofelements wherein most of the electrons flow between a first element anda power carrying element and at least one additional element regulatesthe intensity of the electron flow, a relatively large chassis havinghigh electrical and thermal conductive properties, meanscoupling analternating input signal to the valve across said first element and'said additional element, and means coupling an output signal from saidvalve between said power element and one of said first andadditionalelements whereby that one of said first and additionalelements is in common circuit connection between the alternating inputand output signals, means providing a large area high heat, conductionpath for physically and electrically connecting said power carryingelement to the chassis thereby to conduct away the A.-C. signals, saidinput signal coupling means including an inner cavity container forminga shielded enclosure about the portion of the valve connections for saidfirst and an additional element and including a means for coupling theinput signal within said inner cavity member to energize said enclosedelements, and said chassis including an outer cavity container directlyconnected to the power element and enclosing said inner cavity, andtuned circuit means coupled between the outer'cavity container and theinner cavity container for deriving said 6; A high frequency vacuum tubecircuit of increased power handling capacity comprising:

a vacuum tube having a plate, cathode, andgrid electrodes, i I V Q acontainer of high electrical conductivity coupling the grid and cathodeelectrodes of the tube, a second container of high thermalelectricalconductivity for coupling the plate electrode of the tube tothe first container, 1 V v said second container being grounded to aheat sink to provide a common electrical ground and a' common thermalheat sink at "said plate electrode, a signal'transrnission path having ashielding conductor for coupling an input signal within the first ofconducting material having one end directly connected to the wall of thefirst container and having its interior opening into'the firstcontainer, 7 a

and means for applying the input signal within the hollow, tube toenergize the grid-cathode circuit of the tube. V V V 8. In the highfrequency circuit of claim 6, said signal transmission path comprising acoaxial line having an inner conductor and an outer shield with theinner conductor being coupled to .one of said grid and cathode irectlyconnected electrodes and said outer shield being to the walls of thefirst container.

9. A high frequency electronic circuit for a planar vacuum tube having aplate, a grid, and a cathode, a first cavity forming conducting wall forcoupling the grid and cathode of the tube and having the conducting walldirectly connected to one of the cathode and grid electrodes,

21 second cavity forming conducting wall coupling the plate electrodeand the first cavity wall with the plate electrode being directlyconnected to the sec- 0nd cavity wall,

means for applying direct current energization between the plateelectrode and each of the grid and cathode electrodes,

means for directly connecting the second cavity Wall to a common groundheat sink thereby to provide a direct path for direct and alternatingcurrent conduction, and thermal conduction from said plate electrode tosaid common ground heat sink,

a two channel signal transmission path comprising an input signalchannel and an output signal channel for respectively conveying inputand output signals to the circuit and having an electrical conductorthat is common to both signal channels and shielding each signal channelfrom the other,

said input signal channel being energizable by an in put signal andapplying the input signal within the first cavity forming wall toenergize the grid and cathode circuit of the tube, and said outputsignal channel being coupled between the first and second cavity formingwalls to convey an output signal from the plate electrode to thegrid-cathode circuit of the tube,

and said common electrical conductor for the two channels electricallyshielding the input signal from the output signal.

It}. In the high frequency electronic circuit of claim 9, said twochannel signal transmission path comprising an elongated hollow tube ofconducting material,

means for applyin" said input signal within the hollow tube, and meansfor obtaining the output signal from the wall of the second cavity wallto the outer surface of the hollow tube,

the conducting surface of the hollow tube providing a common electricalconductor to shield the input signal within the hollow tube from theoutput signal outside of the hollow tube.

11. in the high frequency of the circuit of claim said two channelsignal transmission path comprising a coaxial transmission line, havingan inner conductor and an outer shielding conductor,

means for transmitting the input signal between the inner conductor andthe shielding conductor,

and means for obtaining the output signal from the conducting wall ofthe second cavity tube to the outer shielding conductor of thetransmission line,

said outer shielding conductor of the transmission line providin acommon conductor between the input and output signals that shields theinput and output signals from each other.

12. A high frequency vacuum tube circuit of increased power handlingcapacity comprising:

a vacuum tube having a plate, cathode, and grid,

a hollow container of high electrical conductivity coupling the cathodeand grid electrodes of the tube,

a second container of high electrical and thermal concluctivity couplingthe plate electrode of the tube to the first hollow container, saidplate electrode being short-circui-ted to the second container for bothelectrical and thermal conduction therebetween,

a coaxial transmission line having an inner and outer conductor, saidline being arcuately configured along its length,

at one end of said line said inner and outer conductors being coupledbetween said first container and one of said grid and cathode electrodesof the tube to 1G apply an input signal to the grid-cathode circuit ofthe tube, said coaxial line being disposed with respect to said secondcontainer to inductively couple the outer conductor of said line to thewall of said second container thereby to transmit an output signalbetween the wall of said container and the outer conductor of saidtransmission line, whereby the outer condoctor of the coaxialtransmission line is in common to both the input and output signals andelectrically shield-s one from the other. 13. In the circuit of claim12, said coaxial transmission line being elongated at the frequency ofthe input and output signal to provide a lumped inductance along its alength,

means for alternating current coupling one end of the outer conductor ofthe coaxial line to the wall of the second container and directlycoupling the outer conductor of the coaxial line to the wall of thefirst container,

means for applying .an alternating current input signal between theinner and outer conductors of the coaxial line,

and means for obtaining .an alternating current output signal from theouter conductor of the coaxial transmission line to the wall of thesecond container.

14. A high frequency electron tube circuit comprising:

a container of conducting material, an electron tube within thecontainer and having a plate, cathode, and grid electrodes,

said plate electrode being directly connected to the container forelectrical and thermal conduction thereetwecn and said container adaptedto be supported on a grounded heat sink of large thermal capacity,

a signal transmission member having a shielding conductor of sufficientlength to provide inductance at the frequency range of the circuit,

said transmission member extending int-o the container,

said transmission member being coupled .to the gridcathode circuit ofthe tube and means for applying an alternating input signal to thetransmission memher to energize the grid-cathode circuit,

means for applying direct current potential between the shieldingconductor of said transmission member and said container to energize andbias the tube,

means for disposing the shielding conductor of said transmission memberwith respect to the wall of the container to inductively couple theshielding conductor to the walls of the container thereby to provide asignal output circuit for coupling the plate ele ctrode to thegrid-cathode circuit,

capacitor means interconnecting the shielding conductor to the containerto resonantly tune the inductance to the frequency of the output signal,

and means for coupling an output signal from the wall of the containerto the shielding conductor of the transmission member whereby saidshielding conductor is in common to both the input and output signals.

15. A high frequency electron tube circuit comprising:

a container of high thermal and electrical conductivity supported withrespect to a heat sink ground,

an electron tube having a plate electrode directly connected to thecontainer and having a grid electrode and a cathode electrode,

a signal transmission member for conveying a high frequency input signaland having a shielding conduct-or for said signal and serving as oneterminal thereof,

means for applying an input signal to said member at one end andcoupling the other end to energize the grid-cathode electrodes of thetube,

means for disposing said shielding conduct-or along its length ininductively coupled relationship with the container,

assign 1 1 means for capacitively coupling said shielding conductor tothe container near the end proximate the coupling to the grid-cathodecircuit to resonantly tune the inductance provided thereby, means forcapacitively coupling said shielding conductor t-o said container nearthe other end thereof for receiving the input signal, and means forohtaining'an output signal from the plate electrode to the grid-cathodecircuit, said means including means coupled between said container andsaid shielding conductor at a location along said shielding'conductorthat is intermediate the opposite I i ends thereof. I a

' 16.'In the circuit of claim 15, said signal transmission membercomprising a coaxial line having an inner conductor and an outershielding conductor.

17. in a high frequency circuit comprising an electron tube having aplate, control grid and cathode, a high frequency electnomagnetic shieldfor'said tube comprising a heat sink body, means directly connectingsaid plate to the shield to provide conduction therebetween for bothalternating current and direct current signals as I well as thermalconduction, a high frequency cavity coupling said control grid andcathode, a high frequency signal transmission member including a hollowconductor coupled to said cavity,'means for directing an input sig- 7nal within said hollow conductor to energize the control grid andcathode'circuit of thetube, said hollow conductor having a curved outersurface along its length'whereby its outer surface providesa-distributed inductance at the frequency of the alternating currentsignals, capacitor means coupling the outer surface of said hollowconduetor to the heat sink body to tune said distributed inductance,whereby an output signal is derived'from between said plate and saidgrid-cathode circuit across said distributed inductance. Y 5

References Cited by the Examiner UNITED STATES PATENTS ROY LAKE, PrimaryExaminer, V NATHAN KAUFMAN, Exami'n er.

1. IN A HIGH FREQUENCY ELECTRONIC CIRCUIT, AN ELECTRON VALVE HAVING APLURALITY OF ELEMENTS WHEREIN ELECTRONS FLOW TO A POWER CARRYINGELEMENTS FROM A SECOND ELEMENT AND AT LEAST ONE ADDITIONAL ELEMENTRGULATES THE INTENSITY OF THE ELECTRON FLOW, AN INNER CAVITY CONTAINERFORMING AN ELECTRICAL SHIELDED ENCLOSURE FOR SAID SECOND ELEMENT ANDSAID ADDITIONAL ELEMENT AND BEING DIRECTLY CONNECTED TO ONE OF SAIDELEMENTS ENCLOSED, MEANS FOR INJECTING A HIGH FREQUENCY SIGNASL INTO THEINNER CAVITY AND APPLIED ACROSS THE ELEMENTS ENCLOSED THEREIN, AN OUTERCAVITY CONTAINER DIRECTLY CONNECTED TO SAID POWER CARRYING ELEMENT ANDENCLOSING SAID INNER CAVITY, TUNED CIRCUIT OUTPUT MEANS INTERCONNECTINGSAID INNER CAVITY CONTAINER AND OUTER CAVITY CONTAINER, AND OUTPUTTERMINAL MEANS COUPLED TO SAID TUNED CIRCUIT MEANS AND TO SAID OUTERCAVITY CONTAINER FOR CONVEYING AN ALTERNATING OUTPUT SIGNAL.